You could really bring a picnic lunch and enjoy the good part of the day doing the tour of the house and gardens.
depends on how much of the full property you walk. plan for at least 2 hours for the house tour and a walk around the immediate areas around the house with the amazing views. if you want some exercise then walk the trails leading up to the house. it is mostly uphill getting back up to the house, so be prepared for a respectable workout.
A couple of hours for touring the house. Flower garden a short stroll from the house. A great view to the west is a 15-20 minute walk from the house. There are picnic tables by the view point.
The guided tour of the house is 60 - 75 minutes long; add an hour or two for roaming the grounds.
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